Corner joints and methods of forming such joints are described herein.
The structures used to join framing components in a variety of structures such as, e.g., window sashes, window frames, doors, door frames, picture frames, etc. may take a variety of different forms. In some instances, such as, e.g., windows or doors, corner joints may be formed by thermal welding of frame members at each corner. Examples of such a method are described in, e.g., U.S. Pat. No. 5,603,585. In the corner joints disclosed in that reference, the decorative appearance of one side of the corner joint is improved because one of the frame member includes a flange that gives the finished joint the appearance of a mortise and tenon joint structure because the visible joint between the frame members meeting at the corner joint is aligned along the longitudinal axis of one of the frame members.
Although the use of thermal welding to form the corner joints in U.S. Pat. No. 5,603,585 produces joints that are structurally sound and, from one side, have a visually pleasing appearance, thermally welded joints are not without difficulties in the manufacturing process.